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[Teardown and Measurements] Swissonic HAD-1 AD/DA converter + headphone amplifier

Ratio

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Jan 31, 2019
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#1
Hey guys, this is actually my first post on this forum so maybe a little introduction is in place. I am an electrical engineer from Finland and I've been in the headphone audio scene for quite some time now, went through a lot of gear and decided to do some measurements of my own. My measurement system for now is RME ADI-2 Pro and I might be getting something to measure headphones in the future if everything goes well.

I decided to try and make some videos where I open source gear and comment a little bit on the design choices and components I see inside of it with some EMC tips and tricks here and there. And at the end I will include some key measurements and post all of them on this forum.
If this format does not interest people I'll just post measurements on this forum instead as I might be able to find some devices from the European Union or Russia more easily than our good man Amir.

Here is the link to the video
I hope some of you can look past my Finnish accent and some fuckups here and there because it's my first attempt, I would have liked to do a better job but I actually sent the device on its way so I could not shoot some scenes I would have liked to. I promise to do a better job next time :p


The HAD-1 can be bought from Thomann and it's actually quite affordable at 129 € and even cheaper in the case you find a B-stock one. It's a plug and play device, works without drivers. Comes with a 15V external DC power supply.

And here are all of the measurements I took for this device:


ADC

Swissonic HAD-1 Line input.PNG


This is how the line input/ADC of the device performs when fed by the ADI-2 Pro. It could definitely be used for voice chat purposes if you had a mic preamplifier and were missing an audio interface. I can't really come up with other use cases for it other than maybe ripping vinyls but the performance is not great.

Headphone output:

swissonic_1Vrms_headphone_unloaded_spectrum.PNG


1Vrms non loaded headphone output at unity gain. This measurement shows what is to be expected from everything else; the third harmonic is the dominating one and it's around -90 dB. Not that great when looking at the top dogs of todays market. You can see the 100 Hz peak which is double the frequency of the mains here in Finland hinting that the external power supply lets through some AC ripple that gets coupled to the output.

Loaded FR:

30 ohms:
swissonic had-1 FR 30ohm STEPS 1Vrms.PNG


330 ohms:
swissonic had-1 FR 330 ohm STEPS.PNG


unloaded:
Swissonic HAD-1 FR noload STEPS 1Vrms.PNG


Here are three frequency responses for the headphone output: 30 ohms loaded, 330 ohms loaded and unloaded. You can see that the 30 ohms loaded response is on different level than the ones with higher load impedance. This is because of the not so great feature of the headphone output: a whopping 55.5 ohms output impedance. I kept the output of the amplifier constant so the voltage over the load did vary.

THD vs frequency on different loads, 1Vrms output:

30 ohms:
swissonic had-1 THDvsFR 30ohm.PNG

330 ohms:
swissonic had-1 THDvsFR 330ohm 1Vrms.PNG

no load:
swissonic had-1 THDvsFR noload.PNG



THD, CCIF19 IMD and SMPTE IMD vs output voltage on different loads:

THD
Swissonic HAD-1 THDvsOutput.PNG


CCIF19IMD
Swissonic HAD-1 CCIF19 IMD.PNG


SMPTE IMD
Swissonic HAD-1 SMPTE IMD.png


Here the output impedance shows the best on the THD graph: the voltage over the load is the same on each of the load situations but with the 30 ohms load the amplifier output voltage is much higher, resulting in better performance because of higher signal amplitude. The amplifier can get to around 4 Vrms output voltage before it clips to a 330 ohm load.

Line output:

swissonic_lineout_2Vrms_high_2nd.PNG
swissonic_lineout_2Vrms_low_2nd.PNG

Here are two 1 kHz signal outputs where I wanted to show that the second harmonic changes and you can get changes of over 5dB depending on the timing you are taking the measurement. This does not happen for the third harmonic.

Frequency response:
swissonic had-1 lineout FR steps.PNG

The treble rolls off around 0.6 dB from 10 to 20 kHz, no biggie. The output capacitors are dimensioned correctly and there is hardly any sign of the highpass filter, at least when the load is the inputs of my ADI-2 pro.

THD, CCIF19 IMD and SMPTE IMD vs output voltage:

THD
swissonic HAD-1 lineout THDvsOutput.PNG


CCIF19 IMD
swissonic had-1 lineout CCIF19 IMD.PNG


SMPTE IMD
swissonic had-1 lineout SMPTE IMD.PNG

Not much to say here, plots do the talking.


THD vs frequency on the line output:
swissonic HAD-1 lineout THDvsFreq.PNG

There is actually more second harmonic on the line outputs than on the headphone output leading to worse performance near the lower end of the audio band. I actually messed up this measurement as the graph only goes up to 10 kHz.


From the performance of this device you might be able to guess that it uses some older components: the DAC chip is a PCM 1754 and most of the opamps in the signal path are RC4580. Notable mention goes to one NE5532, the opamp we can find in everything from asses to motorboats.

I don't really see any reason for the high output impedance unless it has to do something with the muting circuit on the output. Maybe they wanted to protect low impedance headphones from high output voltages. I tried it using Sennheiser HD800 and I could not turn the volume up to 9 a clock because it was so loud, lowering your Windows volume might be necessary with many headphones. At least I got over the channel imbalance part of the volume potentiometer. At this point I realize that I forgot to take a channel imbalance measurement.

I might have not mention every notion on this written measurement part of the duality so you can find the rest on the video.
Thanks for reading (and maybe watching too) and please do ask and comment on what you think about this kind of content in the future.


On the measurements:
The measurements are taken in a normal home environment. My reasoning behind why this is meaningful is that there are other devices present which allows for electromagnetic interference coupling between devices. This environment is also where most people will use these kind of audio related devices. I did not notice any weird EMC related behavior with this unit.
I didn't have a properly specced artificial load for the loaded measurements and that is why I've stopped early when the THD or IMD starts to rise to be on the safe side.


I welcome all suggestions and comments!

And if you are a fellow European who would like to get your gear measured you can contact me at [email protected]. My equipment is humble but it's enough for measuring many devices.
 

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Joined
Jan 27, 2019
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Location
China
#2
Thank you for your measurement and test!

Just a suggestion, could you make the pics in your post full image? It's quite hard to click on thumbnails and compare them one by one.;)
 

M00ndancer

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#4
Good review, did you try out the optical in to headphone?
 

Ratio

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Jan 31, 2019
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#5
Sadly no, I feel sorry for making it a bit rushed. However I feel like with the performance numbers being like this the optical in should be able to do the same numbers.
 
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